ARTESIAN WATER

Evening Post, Volume CXX, Issue 129, 27 November 1935, Page 11

ARTESIAN WATER

WORK WELL AHEAD

READY EARLY NEXT YEAR

TWO SETS OF PUMPS

| Though there is little likelihood that |an additional water supply will be needed for Wellington this summer j (when summer docs come) the artesian supply from the Gear Island wells should be available early in the New Year, unless unforeseen obstacles are met with. When the scheme was put j under way February was stated as Who probable date of completion and that estimate appears to be very near I the mark, notwithstanding that there has been a quite unexpected delay of a few weeks in the delivery of certain of the units of the pumping plant. So busy are British, manufacturers and so heavy is the demand for shipping space to New Zealand that some cf the plant was crowded out from (he boat on which it had been intended to ship it to Wellington, and though the manufacturers of the pumps rushed the cases from Scotland to London in an endeavour to keep faith with tho City Council, only part of it could be stowed. An unusually large shipment of cars, amounting to some hundreds, left little space for cargo lower on the booking list. However, the whole of the plant should be delivered in Wellington by early in December. The 17 or 18 wells at Gear Island are driven and, except for finishing work, have been connected up by buried pipe lines to a single largediameter line which leads to the pumping house at Gear Island. The wells, with one exception, were fully successful, water of excellent quality being tapped at a sufficient artesian pressure to give a combined flow of 4,000.000 gallons per day. The station building is complete and ready for the installation of the pumps and their electric motors when they arrive. The Thovndon Quay pumping station is well ahead and the contractors will be handing the building over in a few days. PRESSURE TANK ON HUTT KOAD. The 00.000-gallon pressure. tank above the Hutt Road, about half-way between the Petone crossing and Ngahauranga, is finished, but there is still the fairly big job of making a double connection between the tank and the 21-inch Wainui main. The tank is in strongly reinforced concrete, rectangular in shape, roofed I over. When the Gear Island scheme is in operation, in times of likely shortage of surface supplies, the Wainui main will be closed by the operation of a valve on the Wainui side of the Gear Island station and the artesian supply will be pumped into the main at a sufficient pressure to carry it along the Petone foreshore and Kutt Road and up to the pressure tank. From there it will flow by gravity to the Thorndon Quay pumping station and will be boosted up to sufficient pressure to flow through the city reticulation or to be lifted to the Bell Road reservoir, from which it will gravitate to city mains as Wainui water does today. There, must, therefore, be two-way connections between the 21-inch main and the pressure tank and again betwnen the main and the Thorndon Quay pumping station, with a system of valve control to : turn the main from surface to artesian supply according to demand. TUNNEL UNDER HUTT KOAD. The making of the two-way connection between main and pressure tank is quite a job,- and when one has gone under the roadway through the tunnel underneath the bitumen surface one realises why tho "Danger, 15 m.p.h." signs have been on the roadside for so long. (Not that one motorist in five takes any notice, for some of them tear past the workmen at anything up to 50 m.p.h.) There are four water mains on the seaward side of the road: the oldtimer, 24-inch cast-iron main laid over 50 years ago (1881) when the first supply was brought to the city from Wainui, a later 21-inch cast-iron main from Wainui (to be used in connection with the Gear Island scheme), the 21-inch steel main from Orongorongo to Karori, and an &-inch company main. All four are fairly close together, and the Orongorongo main is actually right beneath the 24-inch main (at this point, though not at other points along the Hutt Road), and, a few feet further out, are the company main and the 21-inch castiron main. The latter is on a higher level than the 24-inch and Orongorongo pair, so that the connectinglengths (in 18-inch pipe) will have to dive down several feet to pass underneath and will then rise gradually through the tunnel under the pavement to begin the steep climb up the hillside to the pressure tank. CUT ACROSS OLD TUNNEL. This .particular length of the Hutt Road has waterworks history. Before the road was straightened a rocky outcrop, Paparangi Point, shot clear across the present road line and ended well on the present railway bed. The road curved round the outcrop, but when the 24-inch main was laid, 54 years ago, tunnels were cheaper than pipes, and to save pipe length the main was taken through the outcrop by a small tunnel. In 1907 the tunnel collapsed and the main inside was well and truly smashed. The replacement lengths were laid further seaward, in their present position. A Wile further along the road, towards Petone, another outcrop, Rocky Point, reached across what is now the roadway, but, like Paparangi Point, it is just a memory or a matter of record. During the tunnel excavations now in hand the old brickwork and heavy timber beddings for the main were found again and cut through; the broken lengths were removed long ago, a couple of years after the collapse. The going in the tunnel has been very hard, ior the bedrock of the old outcrop is stubborn, though during the few weeks that the metal taken out has been exposed to the air it has |. chown sirrns of rapid crumbling. The 150-year-old culveri-iunnel which car- | vied the main in its original position inircduced a further complication in a si;:cable flow of water, but there was Ino great difficulty in dealing with : this. I Everything is practically ready for Ihe coupling of the, 18-inch connecting pipes and the placing of the control valve to send (he water up to the pro-s-ure tank when Gcnr Island water is beinr; supplied to Ihe city, or slrnii.'ht abend when Wfiinui is n.nnlvinr? tho city, which will be (he rn=o during the nrentcr part of the y-ir. | Tii'l join'ini of lnrTc-dir.mcter mains iis a "one1 deal more thnn a plumbing ;k>:>. for (!i:y refine (o bo bent to fit. nnrl they .hist will not Wretch to overcome a lart half-inch ?;ip. 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